Currently, there are just several kinds of travel adaptors:
1. Single-use adaptor: when in an outgoing travel, the user must know the specification of the local power supply adaptors; otherwise he had to bring all kinds of the different adaptors, which would cause inconvenience.
2. Combined adaptor: before combination, the metal for electrifying often reveals to the outside, if the plug is inserted in the socket by incaution, there is a danger of being shocked. Further, lose of a component is likely to occur to a combined adaptor.
3. Versatile adaptor: such adaptors do not have the disadvantages of the single-use adaptor and the combined adaptor, but use of versatile adaptors is complicated, and the security is also problematic.
Therefore, above-mentioned travel adaptors have disadvantages of too much components, complication in use and inconvenience in operation, and hence cannot gratify the need of different countries, different regions and different service patterns.